1) Which of the following sets is arranged according to increasing base strength?
A) F-, OH-, Cl-
B) F-, Cl-, OH-
C) OH-, F-, Cl-
D) OH-, Cl-, F-
E) Cl-, F-, OH- (my answer)
2) What is the pH of a solution formed by adding 4.3 x 10^-5 moles of KOH in 1 L of water?
A) 4.3 x 10^-5
B) 4.4
C) 9.6 (my answer)
D) 2.3
E) 7
3) The pOH of an aqueous solution is 8. The molar concentration of OH- is:
A) 10^6
B) 10^-6
C) 1
D) 10^-8 (my answer)
E) 10^8
These look good to me. Good work.
1) To determine the increasing base strength, we need to compare the strength of different bases. Base strength is determined by the ability to accept protons (H+ ions). The stronger the base, the stronger its ability to accept protons.
In this case, we are comparing the bases F-, OH-, and Cl-.
To determine the order, we need to consider their conjugate acids, HF, H2O, and HCl. The strength of the acid is inversely proportional to the strength of its conjugate base.
The order of increasing acid strength is:
HF < H2O < HCl
Therefore, the order of increasing base strength is:
F- < OH- < Cl-
So, the correct answer is option C: OH-, F-, Cl-.
2) The pH of a solution is a measure of its acidity or basicity. The pH scale ranges from 0 to 14, with values less than 7 indicating acidity, values greater than 7 indicating basicity, and a pH of 7 indicating neutrality.
To find the pH of a solution formed by adding 4.3 x 10^-5 moles of KOH in 1 L of water, we need to determine the concentration of OH- ions in the solution.
The molar concentration of OH- ions can be calculated using the equation:
[OH-] = moles of OH- / volume of solution (in L)
In this case, [OH-] = 4.3 x 10^-5 moles / 1 L = 4.3 x 10^-5 M
To find the pH, we can use the equation:
pOH = -log [OH-]
In this case, the pOH of the solution is given as 8. To find the pH, we can subtract the pOH from 14 (since pH + pOH = 14):
pH = 14 - pOH = 14 - 8 = 6
Therefore, the pH of the solution is 6. The correct answer is option E: 7.
3) The pOH of a solution is a measure of its basicity. It is the negative logarithm of the concentration of OH- ions in the solution. The pOH scale is the inverse of the pH scale, with values greater than 7 indicating basicity and values less than 7 indicating acidity.
In this case, the pOH of the solution is given as 8. To find the molar concentration of OH- ions, we can use the equation:
[OH-] = 10^(-pOH)
Substituting the given pOH value:
[OH-] = 10^(-8)
[OH-] = 10^(-8) M
Therefore, the molar concentration of OH- ions is 10^(-8) M. The correct answer is option D: 10^-8.